March 13 (HealthDay News) -- About 61 million American adults are at high risk for vision loss, and many of them don't have access to eye care, a new study finds.

U.S. Centers for Disease Control and Prevention (CDC) researchers analyzed data on vision from 30,920 people age 18 and older who took part in the 2002 National Health Interview Survey. Of those people, 16 percent were age 65 or older, 6.5 percent had diabetes, and 19.5 percent had vision or eye problems.

Based on those percentages, the researchers estimated that 61 million Americans are at high risk for vision loss.

Of those, one in 12 cannot afford eyeglasses when needed, and about 50 percent don't get annual dilated-eye examinations, in which eye drops are used to widen the pupil and allow a more thorough inspection of the eye.

"Among the high-risk population, the probability of having a dilated-eye examination increased with age, education and income," the study authors wrote in the March issue of the journal Archives of Ophthalmology.

"The probability of receiving an examination was higher for the insured, women, persons with diabetes and those with vision or eye problems. Approximately five million high-risk adults could not afford eyeglasses when needed; being female, having low income, not having insurance and having vision or eye problems were each associated with such inability."

As the U.S. population ages, preventive eye care services will become an increasingly important public health issue.

"Many conditions causing visual impairment and blindness are often asymptomatic in their early, treatable stages," the authors noted. "There is substantial inequity in access to eye care in the United States. Better targeting of resources and efforts toward people at high risk may help reduce these disparities."